Conventional vacuum cleaners usually contain a dust collector in the form of a dust bag which is more or less unstable in shape and is continuously filled with dust during operation of the vacuum cleaner. In the vacuum cleaner, the dust bag is enclosed by a volume referred to as a dust chamber. The dust chamber on the one hand provides an abutment for the dust bag, and thus functions to stabilize the dust bag during operation of the vacuum cleaner. On the other hand, the dust chamber also serves to guide and direct the substantially dust-free air flow emerging from the dust bag. However, when the dust bag is acted upon by an air flow, the sides of the dust bag lay partially against the walls of the dust chamber, thereby impeding optimum flow through the bag. As a result, the fleece layers of the dust bag, or the dust bag itself, can sometimes not be optimally loaded with dust, which reduces the service life of the dust bag. The dust chamber, as it were, determines the shape of the dust bag when the bag is acted upon by the air stream generated by the fan. In addition, a dust deposit formed during vacuuming is not thrown off the inner surfaces of the dust bag when turning off the vacuum cleaner fan. This also has a negative effect on the service life and the uniformity or evenness of the suction power.
German Patent Application DE 10 2008 045 683 A1 describes a dust filter bag surrounded by a net lying against the outer surface of the bag wall. The extensibility of the net is less than that of the bag wall.
U.S. Pat. No. 4,145,196 is directed to optimizing a filter element for a vacuum cleaner and aims at preventing damage to the filter element or a filter fleece thereof. The filter element includes a sack on the inner side of which is disposed the filter fleece. A spacer having a corrugated surface is provided between an outer housing and the filter element. During operation, the filter element lies against the crests of the corrugated surface. Thus, the corrugated surface and the crests thereof are functionally substantially equivalent to rib-shaped structures, such as the dust chamber ribs extending into a dust chamber of current vacuum cleaners. Both are intended to prevent large-area contact between the dust bag, or the respective sack and filter fleece described U.S. Pat. No. 4,145,196, and structural features of the vacuum cleaner housing, and thus to permit continued flow therethrough. In U.S. Pat. No. 4,145,196, in order to stabilize the filter element, a grid-like stabilizing structure is provided for the sack, and the mesh width of the grid is smaller than the distance between two adjacent crests of the corrugated surface of the spacer. The grid is intended to prevent an otherwise possible movement of portions of the filter fleece into valleys between two respective adjacent crests of the corrugated surface. Such reduction in mobility, in turn, is intended to prevent damage to the filter element.
FIG. 1 shows, in a simplified schematic view, a vacuum cleaner 1 having a dust bag 10 mounted in a dust chamber 2. A fan 4 generates an air stream 5 that passes through vacuum cleaner 1 and thus also through dust bag 10. Air stream 5 is supplied to dust bag 10 through a hose 6 and a bag opening 11.
FIG. 2 illustrates, in a simplified schematic view, the basic design of a conventional dust bag 10. In addition to the actual fleece 13 for collecting in particular small dust particles, dust bag 10 also has, on its upper surface, a static net-like supporting structure 12 which mechanically stabilizes bag 10 and, moreover, protects the dust bag 10 from damage when vacuuming sharp items.
FIG. 3 shows a special, structured embodiment of a fleece 13 of a dust bag 10. Fleece 13 has a wavy or hump-shaped configuration in order to provide a larger filter area and thus a higher dust holding capacity.
FIG. 4 shows a top cross-section through vacuum cleaner 1 and its dust chamber 2, illustrating the spatial arrangement of dust bag 10 in dust chamber 2. Dust bag 10 is supported at various points by dust chamber ribs 3, which prevent dust bag 10 from laying against the walls of dust chamber 2 in some sections or entirely, which would considerably impair the flow through dust bag 2. Nevertheless, when vacuum cleaner 1 is in operation and air stream 5 acts on the dust bag, the bag extends into the regions between ribs 3 of dust chamber 2 and partially contacts the walls of dust chamber 2.
Thus, such a construction does not provide any solution that would prevent dust bag 10 from laying against the walls of dust chamber 2.